We have previously shown, using the rate theory of void swelling, that it should be possible to reproduce the evolution of the high-temperature gas-assisted void swelling peak observed in neutron-irradiated 316 austenitic steel using the planned dual-beam irradiation facilities. However, the rate-theory formulation does not include a cavity nucleation model; hence cavity densities obtained from experiments with preinjection of gas before heavy ion irradiation are traditionally input to the model. Furthermore, swelling is known to be sensitive to cavity densities and no values are presently available from dual-beam experiments.

Therefore, in the present study we calculate cavity densities using a homogeneous nucleation model previously developed for fission gas bubbles in nuclear fuels, and compare the calculated void swelling using these cavity densities with the swelling results previously obtained using the preinjected experimental values.